1. Field of the Invention
The invention relates to a structural member and to a structure made with the structural member.
2. Description of the Prior Art
In recent years, much effort has been directed to the development of environmentally friendly structural products. Such structural products contain significant percentages of regenerable and/or recycled materials.
A structural product containing a substantial percentage of regenerable material is taught in U.S. Pat. No. 4,947,611. This patent discloses a wall panel containing clay in combination with straw, chaff and palm material. The panel may optionally include hemp.
U.S. Pat. No. 5,177,924 illustrates a structural product which can comprise straw, chaff and/or rice husks. The product further comprises mineral additives as well as cement, lime and/or gypsum.
A box-like structural product with an interior core of sawdust, rubber or waste fiberglass is shown in U.S. Pat. No. 4,301,198. The box-like product has a rigid exterior skin made of a reinforced plastic binder such as fiber-reinforced polyester, epoxy or polyurethane. The binder penetrates the box-like product to contact the core in adhesive relationship.
U.S. Pat. No. 5,241,795 teaches a structural product made from paper sludge, repulped waste paper or virgin paper pulp. This material is mixed with clay or portland cement, or with animal protein adhesives, or with manufactured resins or polymers.
A panel made up of slats composed of recycled pultrusion polyolefin high density polyethylene is disclosed in U.S. Pat. No. 5,367,844. Each slat contains 85 percent or more of the recycled material.
U.S. Pat. No. 5,482,550 discloses a structural product consisting of portland cement, recycled and ground expanded cellular polystyrene, ground cellulosic fiber, fly ash, silica fume, bentonite, water, air entrainer, paraffin wax emulsion and rubber emulsion. The product serves as a roofing material.
A wall panel made up of layers each of which contains a different recycled material is taught in U.S. Pat. No. 5,724,783. The recycled materials in the panel include used fiberglass insulation, recycled polystyrene, rubber tires and old carpets.
The recycled materials are broken down and then mixed with portland cement, microsilica, sand and water before being placed in the panel.
U.S. Pat. No. 5,729,936 teaches the production of a prefabricated panel by compressing a fiber slurry composed of waste paper, waste cardboard, straw, leaves and grass clippings. The slurry, which may contain waterproofing agents, fire retardants, antifungal agents and insecticides, is poured into a press form for compression,
As seen from the preceding overview of the prior art, the use of recycled thermoplastic plastics in structural products is limited. Thermoplastic plastics are those which soften or fuse when heated and which harden and become rigid when cooled. Plastics of this type are in contrast to thermosetting plastics which become permanently hard and rigid when heated or cured and which are thereafter relatively incapable of softening or fusing upon heating.
Although the use of recycled thermoplastic plastics in structural products is limited, items made of such plastics constitute one of the largest sources of raw material from recycled matter. A plastic number coding is utilized to separate categories of plastic according to their chemical composition properties, and recyclability, A large number of recycled plastic items (milk and water jugs, detergent bottles, margarine tubs, bags and yogurt containers) are composed of high and low density polyethylene classified with Codes 2 and 4. Similarly, many items (prescription bottles and plastic lids) consist of polypropylene classified with Code 5.
Accordingly, there is still a need for new ways of utilizing recycled thermoplastic plastics. This disclosure is directed to the utilization of such plastic matter as a major component of structural products.